Drop bar multi-break series contact oil switch



S p 22, 1964 E. l. WESTMORELAND 3,150,246

DROP BAR MULTI-BREAK SERIES CONTACT OIL SWITCH Filed NOV. 2, 1961 5 Sheets-Sheet 1 cm A we INSULA /O INVENTOR msumrnvs 49 3903-95493 Edward wesrmorelan ATTORNEY Sept 22, 1964 E. l. WESTMORELAND 3,150,246

DROP BAR MULTI-BREAK SERIES CONTACT OIL SWITCH Filed Nov. 2, 1961 5 Sheets-Sheet 2 INVENTOR Edward I. Wesfmorelond ATTORNEY p 1964 E. WESTMORELAND 3,150,245

DROP BAR MULTI-BREAK SERIES CONTACT 01L SWITCH Filed NOV. 2, 1961 3 Sheets-Sheet 3 INSULAT/O/V FIG. 4.

INVENTOR Edward I. Wesfmoreland ATTORNEY 3,150,246 DROP BAR MULTI-BREAK SERIES CONTACT OIL SWITQH Edward 1. Westmoreland, 3i) Newtield St., Plymouth, Mass. Filed Nov. 2, 1961, Ser. No. 14?,661 '7 Claims. (Cl. 200-145) This invention relates to an improved heavy duty oil switch of the drop bar type providing a minimum of four series breaks and a positive acting oil flow arc extinguisher for at least one of said breaks.

It is well known in heavy duty oil circuit breaker design that to provide a plurality of series breaks effective upon the opening of the circuit breaker reduces the load requirements on each contact when interrupting heavy currents at high voltages, and is particularly desirable in order to obtain short arcing times when interrupting low values of short circuit current or when dropping lines. The only design to provide such multi-break operation is by means of rotating contact elements, that is, oil switches in which the central post carrying the movable contacts is rotated in order to separate the movable units from the stationary contacts. At the high operating speeds required for modern service conditions,

A United States Patent this imposes a very great mechanical strain upon the contact supporting elements and upon the torque rod, which in practice has tended to limit the maximum size of the circuit breakers, and also to greatly increase their expense in order to provide the necessary strength and rigidity. Since three stationary contacts must at some point he supported by standard porcelain entrance bushings, this imposes a further limitation upon the mechanical design, since most effective entrance bushings have limited mechanical strength, particularly in tension and under shear stress. The rotating blade type of construction imposes severe tension and shear requirements upon the entrance bushings, and this is therefore a definite limiting factor in the design of such circuit breakers. Drop bar construction is commonly employed for twobreak oil switches, in which the drop bar carries a contact at each end, but this type of circuit breaker has not heretofore been successfully employed for full travel multi-break series contact oil switch assemblies, due to the mechanical design problems involved.

It is a major object of the invention to provide a full travel multi-break series contact oil switch assembly of the drop bar type, which is simple and inexpensive in construction, and which imposes no undue mechanical strain upon the insulating supporting elements due to the novel design employed. A further object is to provide an oil flow arc extinguisher for a drop bar multibreak circuit breaker, wherein the action of the drop bar in opening the circuit contacts also forces oil by positive pump action through at least one and preferably two of the contact assemblies being opened without relying upon gas pressure generated by the are itself, which is known under some conditions of operation to be unreliable. The positive action oil pump provided by the present invention does not depend upon line conditions, and is always effective whenever the switch opening mechanism is operated, to remove ionized gases and reduce arcing to a minimum. It will be understood that the term oil switch is generic, and includes heavy duty switches using other fluids commonly used for this purpose as Well as oil.

Another object is to provide a construction as above described in which the oil pump serves also as the necessary thrust bearing and support for the drop bar shaft, thus providing a dual function for this structure. A further object is to provide a circuit breaker requiring ice less tank oil than conventional oil circuit breakers of similar capacity due to the compact arrangement of parts, and to the fact that arcing and carbonization of the oil are reduced by the multiple break construction.

It is also an object to provide an oil circuit breaker which is easily inspected and cleaned during maintenance, and one in which all parts of the insulating supporting structure can be made available for cleaning during maintenance. A further object is to provide a construction in which the thrust support for the drop bar shaft is at the lowest possible point, ensuring smooth and vibration-free operation. Another object is to provide a multiple break oil switch assembly of sturdy design utilizing a simple drive rod mechanism combined with a pump so as to have the minimum possible number of separate parts.

The specific nature of the invention as Well as other advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings, in which:

PEG. 1 is a schematic perspective view showing the essential elements of a circuit breaker embodying the principle of the present invention;

FIG. 2 is an exploded View of the central insulating support for the switch operating mechanism, showing the manner in which it may be adjusted relative to the top of the oil tank;

FIG. 3 is a sectional View taken on line 3-3 of FIG. 1;

FIG. 4 is a view similar to FIG. 1 showing the invention applied to a six-break circuit breaker; and

FIG. 5 is an elevation of a circuit breaker according to the invention, partly broken away to show the general arrangement.

Referring to FIG. 1, the main circuit breaker contacts generally indicated at 2 and 3, are supported by conventional ceramic insulators 4 and 6 respectively, and lead to the conventional oil circuit breaker terminals 5 protruding from the top of the tank housing the equipment, as shown in FIG. 5. Movable contact elements 7 and t5 cooperate with contacts 2 and 3 respectively, and are carried by an insulated drop bar assembly generally indicated at 9, which is vertically reciprocated to engage and disengage the contacts by rotation of shaft 11 through a short angle in one direction or the other. Shaft 11 carries lever 12 which hingedly engages the upper end of insulated drive rod 13. The lower end of rod 13 hingedly engages drop-bar shaft 14 to reciprocate this shaft as lever 11 is rotated by conventional operating mechanism, not shown.

The elements above described do not differ greatly from conventional drop-bar circuit breaker construction, which, however, provides only two breaks in series when the mechanism is operated. In order to provide additional breaks, in accordance with the present invention, an insulated cantilever support 16 is constructed as best shown in FIG. 2, of two, halves l7 and 18 which are assembled as shown to form a generally cone-shaped supporting member with separations between the two halves for inspection and cleaning during maintenance. The two halves 17 and 13 may be secured at the narrow bottom portion by any suitable fastening means, shown as two bands 19 and 21, While at the wide top portion, the insulated cone 16 is preferably fastened by screws 22 to a metal ring 23 having a flange 24 perforated to accommodate adjusting bolts 26, and having also a generally spherical bearing surface 27 adapted to engage a complementary bearing surface 28 on flange ring 29. It will be apparent that by suitably adjusting the nuts 31 on their respective bolts 26, the cone 16 can be angularly adjusted to assure that its small bearing end is accurately positioned. This feature is useful because of the necessity for precise alignment of the switch contacts. Flange ring 29 is in turn Welded in any desired manner to cup 31 which is in turn fixed to the top 30 of the switch tank or housing, which may be of any conventional design. Drive shaft 11 passes through mp3 whereby it is properly positioned with respect to drive arm '13 as .shown in FIG. 1. Any suitable means of sup porting drive shaft 11 may be employed, as will be apparent to those skilled in the art.

The narrow end of cantilever support 16 is fastened to cylinder 32 by any suitable means shown as screws 33, which also pass through securing ring elements 19 and 21. Cylinder 32 is fixed to central conductor 34, which carries at its end a second set of stationary switch contacts generally indicated at 36 and 37, which may be similar in construction to contacts 2 and 3, except that the respective interiors of contact housings 38 and 39 communicate with the interior of cylinder 32 by way of passages 41 and 42 drilled or otherwise formed in the arms of the central conductor 34.

Drop bar shaft 14 carries near its upper end piston 43 which reciprocatcs within cylinder 32 as the switch is opened and closed. Ports 4d are PI'OViJfid nearthe upper end of the cylinder to permit entry of oil from the inte rior of the switch tank to the cylinder when the piston is in the upper position shown in FIG. 3 by relieving any trapped gas, and to allow fast initial speed to are tips before pumping action starts. a

It will be apparent that when drive shaft 11 is operated to open the switch, piston 43 will force the oil in the cylinder 32 through the passages 41 and 42, past the switch contacts as they are disengagingyandthrough ports 46, thus providing oil :under high pressure and positive feed to extniguish the are formed at the contacts during the opening of the circuit breaker. Although drive rod 13 is shown in FIG. 1 in the closed position, the drop bar 9 is shown in the open circuit position for greater clarity.

It will be apparent that when the circuit breaker is closed, current can flow from stationary contact 2, movable contact 7, bridging member 43, movable contact 49, through movable contact 36, central conductor 34, stationary contact .37, movable contact 51, bridging member 52, movable contact 8, to stationary contact 3. The conductive bridging members 48 and 52 are supported on drop bar shaft 14 by the insulating drop bar members 53 and 54, which can readily be made as strong and rigid as necessary at the point of connection to the drop bar shaft 14, where the greatest strain occurs.

In order to further assure accurate alignment and orientation of the contacts, upper hinge member 56 of drop bar shaft 14 moves within guide plates 57 which are rigidly fastened to the top of cylinder 32, and thus act directly on the fixed drop-bar elements to insure positive orientation.

The cone 16 may be suitably made of molded or pressed insulating material having great tensile and compressive strength, such as micarta duck, and due to its conical configuration, provides a structural member of great strength having a very long insulation path to minimize leakage effects. The conical configuration also provides the necessary rigidity for the central conductor 34 and its stationary contacts 36 and 37. Suitable sealing rings may .be provided for the oil pump as indicated by O-ring as indicated at and '61.

FIG. 4 shows the invention applied to a six-break switch. Since the construction is essentially similar to that previously described, corresponding elements of the drawing are similarly numbered, with a prime added. There are in this case two central conductors 34- and 34" separated by an insulating block 62, which is centrally apertured to receive cylinder 32', the piston element being exactly as previously described. An additional conductive bridging element 63 is also required for the extra set of contacts, and an additional set of strength and rigidity.

The oil pump piston slides in the cylinder toserve also as a slide hearing at the lowest point of support, thus insuring vibration-free and smoothly-fitting operation.

it will be apparent that the embodimentsshown are only exemplary and that various modifications can be made in construction and arrangement within the :scope of my invention as defined in the appended claims.

I claim:

l. A multiple series break oil circuit breaker comprising an oil tank having a roof portion, two main stationary contacts supported by and insulated from said roof pontion, and extending into said tank in horizontally spaced relationship; a horizontal drop-bar of insulating material extending substantially between said contacts, a conductive bridging element carried at each end of said drop bar, an upwardly extending movable contact at each end of each said bridging element, one of said contacts on each bridging element engaging respectively one of said main stationary contacts; two further stationary contacts spaced from said main stationary contacts and respectively engaged by the remaining movable contacts of said bridging elements; rigid horizontal central conductor means connecting said last two stationary contacts; a single insulating means extending downwardly from the center of said roof portion for supporting said central conductor means from the roof portion of the tank; and actuating means extending through said single insulating means for moving said drop bar vertically downward in said oil tark to simultaneously disengage all of said movable contacts from said stationary contacts.

' 2. The invention according to claim 1, said insulating means being supported by and depending downwardly from said roof portion and engaging said central con duotor intermediate its ends; said actuating means including a vertical rod fixed to said bar centrally intermediate its ends and sl'idably passing through and laterally supported by said insulating means at the region of its engagement with said central conductor.

3. The invention according to claim 2, including cylinder means immersed in said oil tank and carried by said insulating means, piston means carried by said vertical rod'for movement within said cylinder mean upon movement of said drop bar, and means for directing fluid from said cylinder means to at least one of said further stationary contacts. s

4. The invention according to claim 3, said cylinder means being fixed to said horizontal central conductor; said in ulating means comprising a hollow, generally cone-shaped cantilever assembly of insulating material supported at its wide base end by said roof portion, the narrow end or" said cone-shaped assembly being open and encircling said cylinder means and rigidly fastened thereto, whereby said insulatingmeans supports said central conductor and the contacts carried thereby. V

. 5. The invention according to claim 4, and means for adjustably fastening said cone-shaped assembly to said roof portion to adjust the angle of said cone-shaped member with relation to said roof portion.

6. The invention according to claim 5, said coneshaped insulated cantilever member being composed of two similar halves, each separately removable.

7. The invention according to claim 1, said horizontal drop bar having three leg portions extending in generally Y-shaped fashion from a common center to provide three ends on said drop bar, each end carrying a bridging element bearing two upwardly extending movable contacts; there being two said rigid horizontal conductor means each carrying two further stationary contacts and two entrance bushing contacts to thereby provide six stationary contacts and six movable contacts, said bridging elements and horizontal conductor means being arranged to provide a series switching circuit having six series breaks between the main contacts which are simultaneously effective when the drop bar is lowered to open the circuit.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A MULTIPLE SERIES BREAK OIL CIRCUIT BREAKER COMPRISING AN OIL TANK HAVING A ROOF PORTION, TWO MAIN STATIONARY CONTACTS SUPPORTED BY AND INSULATED FROM SAID ROOF PORTION, AND EXTENDING INTO SAID TANK IN HORIZONTALLY SPACED RELATIONSHIP; A HORIZONTAL DROP-BAR OF INSULATING MATERIAL EXTENDING SUBSTANTIALLY BETWEEN SAID CONTACTS, A CONDUCTIVE BRIDGING ELEMENT CARRIED AT EACH END OF SAID DROP BAR, AN UPWARDLY EXTENDING MOVABLE CONTACT AT EACH END OF EACH SAID BRIDGING ELEMENT, ONE OF SAID CONTACTS ON EACH BRIDGING ELEMENT ENGAGING RESPECTIVELY ONE OF SAID MAIN STATIONARY CONTACTS; TWO FURTHER STATIONARY CONTACTS SPACED FROM SAID MAIN STATIONARY CONTACTS AND RESPECTIVELY ENGAGED BY THE REMAINING MOVABLE CONTACTS OF SAID BRIDGING ELEMENTS; RIGID HORIZONTAL CENTRAL CONDUCTOR MEANS CONNECTING SAID LAST TWO STATIONARY CONTACTS; A SINGLE INSULATING MEANS EXTENDING DOWNWARDLY FROM THE CENTER OF SAID ROOF PORTION FOR SUPPORTING SAID CENTRAL CONDUCTOR MEANS FROM THE ROOF PORTION OF THE TANK; AND ACTUATING MEANS EXTENDING THROUGH SAID SINGLE INSULATING MEANS FOR MOVING SAID DROP BAR VERTICALLY DOWNWARD IN SAID OIL TANK TO SIMULTANEOUSLY DISENGAGE ALL OF SAID MOVABLE CONTACTS FROM SAID STATIONARY CONTACTS. 